Detachable blade core bit



Dec. 5, 1939. e. PURNELL DETACHABLE BLADE CORE BIT Filed July 5, 1938 2 Sheets-Sheet l gar Pam 44. Wfw mgm (1 Noun/1 9 Dec. 5, 1939. s. PURNELL DETACHABLE BLADE CORE BIT Filed July 5, 1938 2 Sheets-Sheet 2 6w uk/v u.

Patented Dec. 5, 1939 DETACHABLE BLADE CORE BIT Guy Parnell,

Angleton, Tex.

Application July 5, 1938, Serial No. 217,346

4 Claims.

My invention relates to well drills and particularly to well drills having scraping blades thereon. It has particular reference to core bits although, as will be obvious, certain features of the 5 invention are adapted for any type of scraping or drag bit. I

It is an object of the invention to provide a drill head having detachable blades thereon which may be removed after being worn and rel placed by other blades, thus making it unnecessary to discard the head because of the dull blades.

It is a further object of the invention to provide a means of attaching the blades to the drill head which will maintain the said blades rigidly in place while in use.

It is a further object of the invention to provide a core drill bit in which the seat for the core barrel is removable and replaceable along with the cutting blades.

It is a further object of the invention to provide .means for delivering the stream of flushing fluid at a point in advance of the cutting blades so that the cuttings may be efiectlvely washed from the blade.

For a clear understanding of the device and the advantages thereof reference is made to the drawings herewith wherein:

Fig. 1 is a side elevation of a core bit employing my invention.

Fig. 2 is a similar view taken at right angles to the view shown in Fig. 1.

Fig. 3 is a bottom plan view of the device shown in Fig. 1.

Fig. 4 is a similar bottom a three-blade bit.

Fig. 5 is a side view similar to Fig. 1 taken in central longitudinal section.

Fig. dis a transverse section taken on the 40 plane 6-6 of Fig. 5.

Fig. 7 is a side elevation of the blades and core cutter removed from the head.

Fig. 8 is a top plan view of the cutter shown in Fig. 7.

Fig. 9 is a broken detail illustrating one means for securing the blade to the head; and

Fig. 10 is a longitudinal section on the plane III-I0 of Fig. 9. I

I have shown my invention as applied to a core bit having a cylindrical head I with an upper threaded shank 2 thereon for attachment to a drill collar 3. The lower end of the head is tapered downwardly at 4 to a shoulder 5 formed thereon to cooperate with the detachable blade and core cutter. As will be seen from Fig. 2

plan view showing the end of the head below the shoulder 5 is reduced in diameter at 6. The lower end of the reduced portion is frusto-conlcal. the lower end 1 providing a stop for the detachable blade.

As many blades may be formed on the head as desired. Ordinarily there will be either two or three.

In Figs. 1 to 3, inclusive, I have shown two scraping blades. blades I provide on opposite sides of the head I outwardly projecting wings 8. As will be noted,

To cooperate with these these wings are tapered upwardly at 9 along the cylindrical portion of the head and are extended straight downwardly at III to correspond with the inner wall of the hole. 7

With reference to Fig. 2, it will be noted that the upwardly tapered portion 9 is thicker adjacent the upper end and tapers in thickness downwardly. At a point along the tapered portion of the head'the forward side of the wing 8 is cut away to form a recess II to receive the cutting blade.

This recess extends downwardly to the level of the shoulder 5 where it terminates.

The wing adjacent the recess I I is provided with transverse openings shown as two in number to receive the studs or rivets I2 by means of which the blade is secured to the Wing. The blade assembly is shown best in Figs. 7 and 8. There are two cutting blades I3 and I4 adapted to fit against the wings of the bit within the recesses II The upper ends of the blades are inclined upwardly at a slight angle, as shown at I4.

The lower ends of the blades have a sharpened edge I5, which is inclined forwardly in the direction of rotation, the edge of the blade being inclined toward the observer in Fig. 7 and the blade It being inclined away from the observer.

It is also to be noted that on the rearward side of each of the blades there is a shoulder formed at I6 .which engages below the opposite ridges I9 thereon, which are adapted tofit within grooves on the tapered portion 6 of the head.

Adjacent the lower end there is a shoulder 20 which contacts with the lower shoulder 1 of the head. The fit between the interior of the core cutter head and the end of the bit head is a tight driving fit.

The inner inclined portions 2i of the blades are also engaged tightly against the head of the bit, as indicated in Fig. 5. To

' at 22, thus further reenforcing the assembly.

The blades may be secured to the head by studs or rivets i2, as previously noted, and in such case therearward side of the wing upon the head will be recessed, as shown at 23, and the forward side of the blade will also be recessed, as shown at 24. A'rivet having a head fitting within the recess 23 will be upset on its forward side to fill the conical recess in the forward side of the blade and this makes a rivet attachment. I have shown two of these rivets or studs but a different number may obviously be employed.

As an alternative for the rivets previously noted, I may form the blades with longitudinal openings therein, as shown at 25 in Fig. 7. The openings in the wing 8 will be also recessed and elongated, as shown at 26 in Fig. 10, and an elongated rivet may be employed to secure the blade to the wing. This is done by upsetting the rivet so that it forms a rigid connection, as shown in Fig. 10.

The interior of thecutter head is formed with a beveled seat shown at 21 in Fig. 5. This furnishes a support for the lower end 28 of the core barrel 29. This sea is liable to wear in use and by forming the sea in the removable portion of the cutter it is possible to replace the blades l3 and the core cutter heads I1 and thereby also renew the support 21 for the core barrel.

The flushing fluid which-passes downwardly through the central opening 30 in the head of the drill finds an outlet through downwardly inclined passages 3|, which discharge the flushing fluid through nozzles 32 directly in front of the blades. To form the discharge nozzle I form a laterally inclined projection 33 upon the tapered portion of the head so that the passage 32 may be inclined outwardly toward the cutting blade and more efiiciently wash the cuttings away therefrom.

The construction of the drill in the manner described provides a particularly rigid and substantial structure. The assembly of the cutter blades [3 with the core cutter between them, as shown in Figs. 7 and 8, makes it possible to re-'- move and replace the cutting portion of the drill which is subjected to wear. Furthermore, the manner in which the assembly of cutters may be driven into rigid position on the head and then riveted in place makes any vibration or play between the blades and the drill head impossible. I have therefore a removable assembly of outaieaoac ters which may be mounted and again removed with little difiiculty and which when in position form what is substantially an integral portion of the drill. The further advantages of this construction will be apparent to those skilled in the art.

What is claimed is:

1. A drag core drill including a head tapered downward on the lower portion thereof, a plurality of radial wings on said head, an axial passage through said head, a cutting assembly shaped to fit over the lower end of said head, radial cutting blades on said assembly formed to fit against the forward sides of said wings, a core cutter connecting said blades and formed to fit against the lower end of said head, said core cutter and blades having a driving fit over the tapered end of said head, an inner annular seat in said core cutter to receive a 'core barrel, and means to secure said blades to said wings.

2. A drag core drill including a head tapered downward on the lower portion thereof, a plurality of radial wings on said body, an axial passage through said head, a. cutting assembly shaped to fit over the lower end of said head, radial cutting blades on said assembly formed to fitagainst the forward sides of said wings, a core cutter connecting said blades, said core cutter and blades having a driving fit over the tapered end of said head, projections on said head above each blade, channels for flushing fluid issuing from said passage through said projections in front of each blade, and rivets connecting said blades to said wings.

3. A core drill including a head, a downwardly tapered portion on the lower end of said head, said tapered portion being reduced in outer diameter adjacent the lower end thereof to form an annular shoulder, a core cutter shaped to fit over said reduced end and contact against said shoulder, radial blades secured to said core cutter, wings on said head to support said blades and means to secure said blades to said wings.

4. A core drill including a head, a downwardly tapered portion on the lower end of said head, said tapered portion being reduced in outer diameter adjacent the lower end thereof to form an annular shoulder, a core cutter shaped to fit over said reduced end and contact against said shoulder, a core barrel seat in said core cutter below said shoulder, radial blades secured to said core cutter, wings on saidhead to support said 7 blades and means to secure said blades to said wings. 

